Lysine-directed staining of proteins for MS-based analyses

Abstract

Visualization of proteins and MS-based analyses are elemental tasks in modern biochemistry. Nevertheless, reports about covalent protein dyes and their suitability for subsequent MS experiments remain scarce. In a recent work, we demonstrated that covalent prestaining of proteins with Uniblue A drastically speeds up proteomic workflows. The present study introduces dabsyl chloride as another truly MS-compatible protein stain. Remarkably, although Uniblue A and dabsyl chloride employ different nucleophilic reaction mechanisms, both are highly specific for lysine residues. The predictable peptide modifications allow easy integration into state-of-the-art bioinformatic workflows. Further, lysine-directed derivatizations with hydrophobic reagents such as dabsyl chloride complement the cysteine-directed ALiPHAT strategy for increasing the sensitivity of peptide identifications.